How Age Affects Your Metabolism

Most people notice that staying at the same weight gets harder as they get older. It's not just perception — your metabolism genuinely changes with age. But the reasons are more nuanced than 'your metabolism slows down.'

What Is Metabolism?

Your metabolic rate is the total number of calories your body burns in a day. It has three components: basal metabolic rate (the energy needed to keep you alive at rest), the thermic effect of food (energy used digesting meals), and activity — both deliberate exercise and unconscious movement like fidgeting.

The Muscle Loss Connection

The biggest driver of age-related metabolic decline is muscle loss. Sarcopenia — the gradual loss of muscle mass — begins as early as your 30s and accelerates after 60. Since muscle tissue burns roughly 3 times more calories at rest than fat tissue, losing muscle directly lowers your calorie burn.

Hormonal Changes

Testosterone in men and estrogen in women decline with age. Both hormones support muscle maintenance and fat metabolism. Their decline contributes to body fat redistribution — particularly toward the abdomen — even without weight changes.

What You Can Do

• Strength train consistently — resistance exercise is the most effective way to preserve muscle
• Eat adequate protein — at least 0.7 g per pound of body weight daily
• Stay active throughout the day — reduce sitting time, take walks, use stairs
• Prioritize sleep — growth hormone, which aids muscle repair, is mostly released during deep sleep

Age-related metabolic changes are real but largely modifiable. The research consistently shows that active older adults maintain significantly higher metabolic rates than sedentary peers of the same age.